The secondary objective of this study is to examine the effect on cellular immune function. This will be achieved by investigating phagocytosis activity, natural killer cells which are CD4+, CD8+, CD25+ and CD2+ and CD3+ subsets, the marker of T-cell maturation period., salivary IgA levels, inflammatory markers (plasma - tumour necrosis factor (TNF), IL6, IL1, chemokines and soluble adhesion molecules).